Were fruit seeds really removed to make people less healthy?

There’s no good evidence that seedless fruit was developed to make people sick. Seedless varieties are generally produced through breeding or fruit-setting traits, and plenty of fruits still have seeds. The conspiracy claim doesn’t follow from the fact that some fruits are sold without them.

Two different things are getting mixed together here. A seed may contain compounds that show some biological effect in a lab, but that doesn’t establish that eating it prevents infection or treats a condition. The amount, how the compound is absorbed, and evidence from people all matter.

Supplements are a separate question too. A product being made from fruit seeds isn’t proof that it works, and concentrated products can have risks or interact with medicines. Check the specific ingredient and claim rather than treating “seed-based” as evidence.

Also, “fruit seeds” isn’t one thing. Seeds differ a lot, and some are unpleasant or unsafe to eat in large amounts. I wouldn’t start eating seeds or buying a supplement based on a broad claim about killing microbes. Look for reliable evidence for the particular product and use.